Throughout the fight over President Trump's demand for a border wall, many Democrats and Republicans have insisted on this point. Border security, they say, involves far more than the exact length of walls. It involves Border Patrol agents, technology, immigration rules and much, much more. Lawmakers have expanded the debate beyond the wall as they try to avoid another partial government shutdown, which sounds good - except they do not agree on the other stuff either. And a deadline looms this week. Democratic Senator Jon Tester tells Fox he is hopeful, although not entirely confident.

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JON TESTER: There are bumps in the road. But as long as we stay focused in a bipartisan way, bicameral way to get this done, I'm hopeful we can get it done. Is it a done deal? No, it isn't. And we could end up in a train wreck. It's happened before.

INSKEEP: The president's allies show no interest in repeating the disastrous shutdown, although White House Chief of Staff Mick Mulvaney adds on NBC.

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MICK MULVANEY: Is a shutdown entirely off the table? The answer is no.

KEITH: The big sticking point now is related to Immigration and Customs Enforcement detention beds. Democrats are proposing that there be a cap placed on the number of detention beds. They say that this would force the Trump administration to prioritize arresting and deporting serious criminals, not law-abiding immigrants. They - Democrats really object to the policies that the Trump administration has used for interior enforcement - that is, finding and deporting people who are in the country illegally. Democrats say that they are targeting people with no criminal records in addition to those that do have criminal records.

INSKEEP: Oh. So this is a debate over money, but it's really a debate over policy and how many people should you be going out and detaining.

KEITH: Yes, exactly. Meanwhile, during the government shutdown, the White House had put out a list of things that it wanted in addition to the wall. And they were asking for an additional $800 million over the funding levels that had been set out to add detention beds. They wanted it to go up to 52,000 detention beds.

INSKEEP: Wow.

KEITH: That would be a pretty significant increase over the number that are being used now.

INSKEEP: You know, Tamara, this is really interesting because the debate over the wall, while it took on this huge, symbolic importance, was - I mean, it was a debate over a construction project to add to walls that already exist. It wasn't, on a substantive level, that big a deal. It seems now you have Democrats and Republicans with a real substantive difference.

KEITH: You know, Democrats have described - some Democrats have described the wall in moral terms, saying that it was wrong and morally wrong. Well, now they're on to an issue where they are once again using those types of terms, describing the White House approach, the Trump administration approach to immigration enforcement as cruel and wrong. And then the president is tweeting saying - the Democrats are behaving irrationally, and they don't even want to take murderers into custody - which Democrats would obviously dispute.

INSKEEP: Well, what is the alternative if there is no agreement by Friday, which is the next deadline that lawmakers have set up for themselves?

KEITH: You know, there could be a short-term spending bill. They could say, you know, we're working on it. We're not quite there yet. Let's, you know, kick this can down the road, as they say.

INSKEEP: Oh, OK. Could do that - or the president could get out of this - or try to get out of it - by declaring a national emergency as you've reported elsewhere in the program today.

KEITH: That's right. And the White House has certainly been looking into that and getting ready for that eventuality or that possibility. Republicans in Congress, particularly in the Senate, are not excited about the idea and are essentially pushing on the president, saying don't force us to do something we don't want to do, which would potentially be a rebuke or terminating the emergency.